You could also avoid defining a delegate altogether.
Like this:
public ICollection<string> CheckUserPermissions()
{
List<string> logins = new List<string>();
Action<OleDbCommand> delCmd = cmd =>
{
cmd.CommandText = "SELECT PERMISSIONS.LOGIN FROM PERMISSIONS";
using (var rdr = cmd.ExecuteReader())
while (rdr.Read()) logins.Add(rdr["LOGIN"].ToString());
};
dbExec(delCmd);
return logins;
}
Edit: I actually mean what Servy wrote in the comment on the other answer, but he described it way better.